The present invention is intended for use with hard or "Winchester" disk drives. Hard disk drives are sealed enclosures in which an inflexible platter coated with magnetic material is spun very rapidly. A magnetic read/write head "flies" only a few microns above the disk on an air cushion. One area of increasing importance in hard disk drives is the need to increase efficiency. This is in part accomplished by positioning the heads in closer proximity to the disk in order to increase the speed of response time. In this regard, positioning the heads as close to the disk without touching it, is essential. However, if particulate matter becomes lodged between the disk and the head, the disk drive can be destroyed.
A major concern in maintaining a hard disk drive unit in operating condition is moisture control. This is a concern since water vapor can generate corrosion within the disk drive unit. Also, moisture acts as particulate matter when present in the drive and can impair operation of the disk drive unit.
Typically, the platter or disk spins at a speed of about 3,000 to 36,000 rpms. This results in an internal operating temperature of about 150.degree. F. At this temperature, moisture drawn into the disk drive unit through the breather air filter is burned off. However, when the disk drive unit is not in operation moisture entering the disk drive unit is a concern. In environmentally controlled surroundings the entry of moisture into the disk drive can be minimized. However, many hard disk drives are utilized with smaller personal computers in offices and residential environments where concern with moisture when the drive is shut down can present a much greater problem. To address this problem, many disk drive manufacturers place a desiccant package in their disk drives to absorb moisture. This desiccant package is usually sized to provide moisture absorption throughout the life of the drive. During operation at the typical operation temperature of approximately 150.degree. moisture in the drive is either dissipated or absorbed by the desiccant package. When the drive is not in operation moisture enters the drive by way of diffusion through the hole in the breather or disk drive cover. If the drive is shut down, quite often, it may be possible that the desiccant pack will become saturated.
Accordingly, there is a need for an apparatus which during shut down periods of the disk drive inhibits or extends the rate of time for moisture entering the drive to reach the internal components thereof, thereby facilitating efficient operation of the disk drive unit and eliminating or reducing the amount of desiccant material used.